The 6th and final book in the terrific and internationally bestselling "Tunnels" series. The Styx are sweeping across England, leaving a trail of death and devastation in their wake and it seems that nothing can stop them. But, deep in the centre of the earth, Will and Elliot may just have stumbled upon a way to save the world, as they uncover an ancient secret that is fundamental to all human and Styx life... 'Does it live up to the hype? Yes.' "Daily Express"